It's a fair question. My Mommy friend when we first met was incredibly new to caring for an AB as well. She had been fascinated by the scene for years and had always wanted to take care of an Adult Baby, but had never done so before meeting me. Suffice it to say, she new she wanted to be a Mommy, but didn't know how to go about doing so with a big baby and she certainly didn't know what my needs were as an AB.
The best advice I can give is to get to know the person on a personal level, feel them out, get a vibe for how they would approach caregiving. Just like every AB/Little regresses differently, every caregiver parents and cares differently as well. My Mommy friend is a very sweet, patient and nurturing type of carer, much more content to just relax with baby on her lap rather than run after a toddler and play on her hands and knees all day. Some caregivers are much more kinetic, they like to move around and play with their littles, others are more laid back and natural. I assume, you know your partner well enough to already have a feel for how he would care for you, use that knowledge to guide and ease into your baby and Daddy time together
Another thing you could do is talk to him about what you desire from a Daddy as an AB/Little and what he would be willing to do for you as a Daddy. This seems like a no-brainer, I know, but this is a very good way to come to a mutual understanding of your roles together. Talking with him and running by him what you feel you require from a Daddy can make the dynamic incredibly strong and it'll make sure you are both satisfied by the arrangement. Me and my Mommy friend sat down and talked for hours about what each other wanted to do as a baby and as a Mommy before we actually began engaging with one another in that way.
The last thing I would suggest is that you both take things at a slow and fair pace. I find that if you rush things it can be an awkward and unfulfilling experience for both parties. If possible try to initiate things together when you have the time and feel comfortable with exploring a Little and Caregiver dynamic. If you can't take the initiative then defer to him. Sometimes it is good to let your partner decide when to instigate Baby/Daddy time, it makes things feel more natural, more like a partnership and less like you are imposing your needs upon them. Every time I have gotten together with my Mommy friend for a thorough Mommy and Baby date, it was either mutually agreed upon or something she initiated because she felt the need to care for me and unwind a bit.
All of this is just advice I feel can help you both ease into a Baby/Little and Daddy dynamic more efficiently, as it can be a big step in the relationship or friendship between two people. Your best bet for finding out how to get him to be a Daddy is to think about what it is you want a Daddy to do for you and to ask him directly what he is willing to do for you as your Daddy. Take your time, be courteous to one another and talk things out, you'll get there. Good luck to you
